292 THE ATMOSPHERE AND METEOEOLOGY. 



hurricane are always stronger on the right side of its path, and in the 

 southern hemisphere always stronger on the left, is not sufficient to 

 explain this astonishing contrast between the two halves of the disc 

 of the cyclone. M. Andrau and other Dutch savants have attempted 

 to explain this apparent anomaly. Taken altogether, the hurricane 

 may be considered, they say, as a disc revolving rapidly around its 

 axis. Its natural tendency is to move incessantly in the same plane 

 of rotation, and only the intervention of considerable force can make 

 it incline in one or the other direction. It is true that at the point 

 where it originates over the equatorial seas the cyclone leans more 

 or less strongly towards its source ; but in proportion as it moves 

 towards the pole revolving round an imaginary axis that remains 

 always parallel to itself, it must necessarily lean more and more back- 

 ward, in consequence of the curvature of the globe. While the 

 southern part of the hurricane still sweeps over the waves or the 

 plains, the other part rises gradually to a great height in the atmo- 

 sphere. Soon the upper winds of the tempest no longer make them- 

 selves felt at the level of the soil, and are only indicated by the 

 fall of the barometric column and by the clouds which we see hurry- 

 ing after each other at a great height in the sky. Towards the 50th 

 degree of latitude to the north or south of the equator, the cyclones 

 elevated half-way only touch the earth by the winds of their lower ex- 

 tremity. These winds are the same in the two hemispheres, they blow 

 equally from the north-west, west, and south-west ; but on each side 

 the gyration is accomplished in the opposite direction. 



Piddington, Eedfield, Bridet, Lartigue, and other learned meteor- 

 ologists have drawn up rules of general conduct for mariners surprised 

 by hurricanes, which, when they are followed in time, may save 

 the threatened ship. Warned by the barometer of the approach of 

 the cyclone, the captain must be very careful not to fly at full speed 

 before the storm, in the vain hope of escaping the danger. By pro- 

 ceeding in this way, as terror would counsel him, he would rush pre- 

 cisely into the midst of the tempest and expose his ship to all the 

 fury of the wind and the surf. To escape its violence he ought to 

 manoeuvre, so as to tend obliquely towards the circumference of the 

 storm as far as possible from the central part, where the wind blows 

 with all its force. Unhappily, whatever may be the science of the sea- 

 man and his knowledge of the seas which he navigates, it is often very 

 difficult for him to know beforehand from which side the winds will 

 approach, and what is exactly the orbit which the centre of the 

 cyclone follows across the seas. Nevertheless, if he hesitates too long, 



